提交 ceac1552 编写于 作者: G Graydon Hoare

For #2229, recognize 'again' in place of 'cont', final change pending snapshot.

上级 e20f63d0
......@@ -209,9 +209,9 @@ import export use mod
The keywords in [source files](#source-files) are the following strings:
~~~~~~~~ {.keyword}
alt assert
alt again assert
break
check claim class const cont copy
check claim class const copy
drop
else enum export extern
fail false fn for
......@@ -2034,19 +2034,19 @@ break_expr : "break" ;
Executing a `break` expression immediately terminates the innermost loop
enclosing it. It is only permitted in the body of a loop.
### Continue expressions
### Again expressions
~~~~~~~~{.ebnf .gram}
break_expr : "cont" ;
again_expr : "again" ;
~~~~~~~~
Evaluating a `cont` expression immediately terminates the current iteration of
Evaluating an `again` expression immediately terminates the current iteration of
the innermost loop enclosing it, returning control to the loop *head*. In the
case of a `while` loop, the head is the conditional expression controlling the
loop. In the case of a `for` loop, the head is the vector-element increment
controlling the loop.
loop. In the case of a `for` loop, the head is the call-expression controlling
the loop.
A `cont` expression is only permitted in the body of a loop.
An `again` expression is only permitted in the body of a loop.
### For expressions
......
......@@ -783,7 +783,7 @@ a specific value, are not allowed.
`while` produces a loop that runs as long as its given condition
(which must have type `bool`) evaluates to true. Inside a loop, the
keyword `break` can be used to abort the loop, and `cont` can be used
keyword `break` can be used to abort the loop, and `again` can be used
to abort the current iteration and continue with the next.
~~~~
......@@ -1187,7 +1187,7 @@ Empty argument lists can be omitted from `do` expressions.
Most iteration in Rust is done with `for` loops. Like `do`,
`for` is a nice syntax for doing control flow with closures.
Additionally, within a `for` loop, `break, `cont`, and `ret`
Additionally, within a `for` loop, `break, `again`, and `ret`
work just as they do with `while` and `loop`.
Consider again our `each` function, this time improved to
......@@ -1221,8 +1221,8 @@ each(~[2, 4, 8, 5, 16], |n| {
With `for`, functions like `each` can be treated more
like builtin looping structures. When calling `each`
in a `for` loop, instead of returning `false` to break
out of the loop, you just write `break`. To continue
to the next iteration, write `cont`.
out of the loop, you just write `break`. To skip ahead
to the next iteration, write `again`.
~~~~
# import each = vec::each;
......
......@@ -56,9 +56,9 @@
"trait" "fn" "enum" "iface"
"impl"))
(puthash word 'def table))
(dolist (word '("assert"
(dolist (word '("again" "assert"
"break"
"check" "claim" "cont" "copy"
"check" "claim" "copy"
"do" "drop"
"else" "export" "extern"
"fail" "for"
......
......@@ -42,7 +42,7 @@ fn dsl(l: ast::lit_) -> ast::lit {
}
~[dse(ast::expr_break),
dse(ast::expr_cont),
dse(ast::expr_again),
dse(ast::expr_fail(option::none)),
dse(ast::expr_fail(option::some(
@dse(ast::expr_lit(@dsl(ast::lit_str(@"boo"))))))),
......
......@@ -336,7 +336,7 @@ enum expr_ {
expr_addr_of(mutability, @expr),
expr_fail(option<@expr>),
expr_break,
expr_cont,
expr_again,
expr_ret(option<@expr>),
expr_log(int, @expr, @expr),
......
......@@ -464,7 +464,7 @@ fn fold_field_(field: field, fld: ast_fold) -> field {
}
expr_path(pth) { expr_path(fld.fold_path(pth)) }
expr_fail(e) { expr_fail(option::map(e, fld.fold_expr)) }
expr_break | expr_cont { copy e }
expr_break | expr_again { copy e }
expr_ret(e) { expr_ret(option::map(e, fld.fold_expr)) }
expr_log(i, lv, e) { expr_log(i, fld.fold_expr(lv),
fld.fold_expr(e)) }
......
......@@ -966,8 +966,9 @@ fn parse_bottom_expr() -> pexpr {
} else if self.eat_keyword("break") {
ex = expr_break;
hi = self.span.hi;
} else if self.eat_keyword("cont") {
ex = expr_cont;
} else if self.eat_keyword("cont") ||
self.eat_keyword("again") {
ex = expr_again;
hi = self.span.hi;
} else if self.eat_keyword("copy") {
let e = self.parse_expr();
......
......@@ -304,8 +304,7 @@ fn contextual_keyword_table() -> hashmap<str, ()> {
fn restricted_keyword_table() -> hashmap<str, ()> {
let words = str_hash();
let keys = ~[
"alt",
"assert",
"alt", "again", "assert",
"break",
"check", "claim", "class", "const", "cont", "copy",
"do", "drop",
......
......@@ -1063,7 +1063,7 @@ fn print_field(s: ps, field: ast::field) {
}
}
ast::expr_break { word(s.s, "break"); }
ast::expr_cont { word(s.s, "cont"); }
ast::expr_again { word(s.s, "again"); }
ast::expr_ret(result) {
word(s.s, "ret");
alt result {
......
......@@ -421,7 +421,7 @@ fn visit_expr<E>(ex: @expr, e: E, v: vt<E>) {
expr_path(p) { visit_path(p, e, v); }
expr_fail(eo) { visit_expr_opt(eo, e, v); }
expr_break { }
expr_cont { }
expr_again { }
expr_ret(eo) { visit_expr_opt(eo, e, v); }
expr_log(_, lv, x) {
v.visit_expr(lv, e, v);
......
......@@ -176,7 +176,7 @@ fn cat_expr(expr: @ast::expr) -> cmt {
ast::expr_new(*) | ast::expr_binary(*) | ast::expr_while(*) |
ast::expr_block(*) | ast::expr_loop(*) | ast::expr_alt(*) |
ast::expr_lit(*) | ast::expr_break | ast::expr_mac(*) |
ast::expr_cont | ast::expr_rec(*) {
ast::expr_again | ast::expr_rec(*) {
ret self.cat_rvalue(expr, expr_ty);
}
}
......
......@@ -33,7 +33,7 @@ fn check_crate(tcx: ty::ctxt, crate: @crate) {
tcx.sess.span_err(e.span, "`break` outside of loop");
}
}
expr_cont {
expr_again {
if !cx.in_loop {
tcx.sess.span_err(e.span, "`cont` outside of loop");
}
......
......@@ -470,7 +470,7 @@ fn visit_expr(expr: @expr, &&self: @ir_maps, vt: vt<@ir_maps>) {
expr_assert(*) | expr_check(*) | expr_addr_of(*) | expr_copy(*) |
expr_loop_body(*) | expr_do_body(*) | expr_cast(*) |
expr_unary(*) | expr_fail(*) |
expr_break | expr_cont | expr_lit(_) | expr_ret(*) |
expr_break | expr_again | expr_lit(_) | expr_ret(*) |
expr_block(*) | expr_move(*) | expr_assign(*) | expr_swap(*) |
expr_assign_op(*) | expr_mac(*) {
visit::visit_expr(expr, self, vt);
......@@ -1009,7 +1009,7 @@ fn propagate_through_expr(expr: @expr, succ: live_node) -> live_node {
self.break_ln
}
expr_cont {
expr_again {
if !self.cont_ln.is_valid() {
self.tcx.sess.span_bug(
expr.span, "cont with invalid cont_ln");
......@@ -1457,7 +1457,7 @@ fn check_expr(expr: @expr, &&self: @liveness, vt: vt<@liveness>) {
expr_assert(*) | expr_check(*) | expr_copy(*) |
expr_loop_body(*) | expr_do_body(*) |
expr_cast(*) | expr_unary(*) | expr_fail(*) |
expr_ret(*) | expr_break | expr_cont | expr_lit(_) |
expr_ret(*) | expr_break | expr_again | expr_lit(_) |
expr_block(*) | expr_swap(*) | expr_mac(*) | expr_addr_of(*) {
visit::visit_expr(expr, self, vt);
}
......
......@@ -3644,7 +3644,7 @@ fn unrooted(bcx: block, e: @ast::expr, dest: dest) -> block {
assert dest == ignore;
ret trans_break(bcx);
}
ast::expr_cont {
ast::expr_again {
assert dest == ignore;
ret trans_cont(bcx);
}
......
......@@ -242,7 +242,7 @@ fn mark_for_expr(cx: ctx, e: @expr) {
})
}
expr_alt(_, _, _) | expr_block(_) | expr_if(_, _, _) |
expr_while(_, _) | expr_fail(_) | expr_break | expr_cont |
expr_while(_, _) | expr_fail(_) | expr_break | expr_again |
expr_unary(_, _) | expr_lit(_) | expr_assert(_) | expr_check(_, _) |
expr_if_check(_, _, _) | expr_mac(_) | expr_addr_of(_, _) |
expr_ret(_) | expr_loop(_) |
......
......@@ -446,7 +446,7 @@ fn combine_pp(antec: pre_and_post, fcx: fn_ctxt, &&pp: pre_and_post,
join_then_else(fcx, p, conseq, maybe_alt, e.id, if_check);
}
expr_break { clear_pp(expr_pp(fcx.ccx, e)); }
expr_cont { clear_pp(expr_pp(fcx.ccx, e)); }
expr_again { clear_pp(expr_pp(fcx.ccx, e)); }
expr_mac(_) { fcx.ccx.tcx.sess.bug("unexpanded macro"); }
}
}
......
......@@ -498,7 +498,7 @@ fn find_pre_post_state_expr(fcx: fn_ctxt, pres: prestate, e: @expr) -> bool {
ret join_then_else(fcx, p, conseq, maybe_alt, e.id, if_check, pres);
}
expr_break { ret pure_exp(fcx.ccx, e.id, pres); }
expr_cont { ret pure_exp(fcx.ccx, e.id, pres); }
expr_again { ret pure_exp(fcx.ccx, e.id, pres); }
}
}
......
......@@ -1220,7 +1220,7 @@ fn check_expr_fn(fcx: @fn_ctxt,
fcx.write_bot(id);
}
ast::expr_break { fcx.write_bot(id); bot = true; }
ast::expr_cont { fcx.write_bot(id); bot = true; }
ast::expr_again { fcx.write_bot(id); bot = true; }
ast::expr_ret(expr_opt) {
bot = true;
let ret_ty = alt fcx.indirect_ret_ty {
......
......@@ -57,7 +57,7 @@ fn loop_query(b: ast::blk, p: fn@(ast::expr_) -> bool) -> bool {
fn has_nonlocal_exits(b: ast::blk) -> bool {
do loop_query(b) |e| { alt e {
ast::expr_break | ast::expr_cont { true }
ast::expr_break | ast::expr_again { true }
_ { false }}}
}
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册